Updated: MOTOTRBO GPS in a nutshell

This post was originally published on 17 October 2012 and has been updated a few times since then. The most recent of these updates was on 26 May 2026.

Some MOTOTRBO models have an integrated GNSS receiver. Models with a display allow users to view their current coordinates via the menu. 

On conventional systems, these radios use a protocol called LRRP (Location Request Response Protocol) to send location updates to a predefined Radio ID (i.e. destination address). LRRP uses triggers to schedule GPS updates: these include GPIO event; delta time; delta distance or immediate.

Radios can be configured to automatically send location updates when an emergency alarm or call is initiated.

Current models also support Inband Location which allows the radio to transmit its location embedded within the voice transmission every time the user presses the Push-To-Talk (PTT) button, without needing a separate data transmission.

Location updates are processed by a PC-based application (server). The application user would use this software to send a location request to a radio after which it will send the location updates as required. The server would either be connected to a Control Station or the repeater network. 

This location request, sent from the application, contains information about the triggers: for example, send GPS data every ten minutes or every 1 kilometer, whichever happens first (this is chosen by the operator via the location application).

In principle, the Control Station can be any MOTOTRBO radio - mobile or portable. The radio is connected to the server via a standard USB cable. This radio would be programmed to monitor the radio channel or system.

The alternative to using a Control Station is the MOTOTRBO Network Interface Service (MNIS). This is a Windows-based service that creates a IP tunnel directly to the repeaters, allowing applications to communicate with the radios via the repeater network.

When a radio receives a location request, it stores it and when one of the triggers have been reached, the radio sends a location packet (takes less than 600ms). The GPS is sent as UDP/IP data over the air, to the predefined Radio ID. The Control Station (radio) or MNIS which receives this, forwards it to the server, which displays the radio location on a map. There are different ways to handle the GNSS update, in terms of channels and coordination.

While standard UDP/IP datagrams are still used, MOTOTRBO also supports optimized ways to send location data. Location data can also be sent via CSBK (Control Signaling Block) data  or as High Efficiency Data on dedicated Enhanced GPS Revert channels. This strips out standard IP/UDP overhead and vastly increases the number of location updates the radio system can handle per minute.

Although not GNSS, MOTOTRBO also supports Indoor Location Operation. Radios with Bluetooth can scan for strategically placed third-party Bluetooth Low Energy Beacons. The radio encapsulates this beacon data into the standard LRRP protocol and sends it to the server, allowing dispatchers to map the user's location indoors where GNSS satellite signals cannot penetrate.

Another MOTOTRBO feature which works hand-in-hand with GNSS is ARS (Automatic Registration Service). This causes the radio to send a registration packet every time the user switches on or (optionally) changes site. ARS is also supported in non-GPS models by the way.